Method and apparatus for performing spine surgery

ABSTRACT

Systems and methods are described for correcting sagittal imbalance in a spine including instruments for performing the controlled release of the anterior longitudinal ligament through a lateral access corridor and hyper-lordotic lateral implants.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/799,021, now U.S. Pat. No. 8,287,597, filed on Apr. 16, 2010, whichclaims the benefit of U.S. Provisional Application Ser. No. 61/212,921,filed Apr. 16, 2009 and U.S. Provisional Application Ser. No.61/319,823, filed Mar. 31, 2010, the entire contents of which are allhereby expressly incorporated by reference into this disclosure as ifset forth in its entirety herein. The present application also claimsthe benefit of priority from U.S. Provisional Patent Application Ser.No. 61/319,823, filed on Mar. 31, 2010 and U.S. Provisional ApplicationSer. No. 61/357,951, filed on Jun. 23, 2010, the entire contents ofwhich are each hereby expressly incorporated by reference into thisdisclosure as if set forth in its entirety herein.

FIELD

The present invention relates to implants, tools, and methods foradjusting sagittal imbalance of a spine.

BACKGROUND

A human spine has three main regions—the cervical, thoracic, and lumbarregions. In a normal spine, the cervical and lumbar regions have alordotic (backward) curvature, while the thoracic region has a kyphotic(forward) curvature. Such a disposition of the curvatures gives a normalspine an S-shape. Sagittal imbalance is a condition in which the normalalignment of the spine is disrupted in the sagittal plane causing adeformation of the spinal curvature. One example of such a deformity is“flat-back” syndrome, wherein the lumbar region of the spine isgenerally linear rather than curved. A more extreme example has thelumbar region of the spine exhibiting a kyphotic curvature such that thespine has an overall C-shape, rather than an S-shape. Sagittal imbalanceis disadvantageous from a biomechanical standpoint and generally resultsin discomfort, pain, and an awkward appearance in that the patient tendsto be bent forward excessively.

Various treatments for sagittal imbalance are known in the art. Thesetreatments generally involve removing at least some bone from a vertebra(osteotomy) and sometimes removal of the entire vertebra (vertebrectomy)in order to reduce the posterior height of the spine in the affectedregion and recreate the lordotic curve. Such procedures aretraditionally performed via an open, posterior approach involving alarge incision (often to expose multiple spinal levels at the same time)and require stripping of the muscle tissue away from the bone. Theseprocedures can have the disadvantages of a large amount of blood loss,high risk, long operating times, and a long and painful recovery for thepatient.

In some other treatments, achieving sagittal balance is accomplished byvia an open, anterior approach to position an intervertebral implantbetween two affected vertebrae in order to increase the anterior heightof the spine in the affected region and thereby recreate the lordoticcurve. Effectuating an anterior spinal fusion typically involvesretracting the great vessels (aorta and vena cava) and tissue adjacentto the anterior longitudinal ligament (ALL), then severing the ALL 16 toincrease flexibility and permit insertion of the implant between theadjacent vertebrae. The anterior approach is advantageous in that theALL 16 is generally exposed, allowing the physician to simply dissectacross the exposed portion of the ALL 16 to access the spine. Theanterior approach to the spine can also have the disadvantages of alarge amount of blood loss, build-up of scar tissue near vital organs,and sexual dysfunction in males. Furthermore, depending upon thepatient, multiple procedures, involving both anterior and posteriorapproaches to the spine, may be required.

In contrast, a lateral approach could be used to access a target spinalsite, remove the intervertebral disc between two affected vertebrae, andinsert an intervertebral implant. A lateral approach to the spineprovides a number of advantages over the posterior and anteriorapproaches to the spine. Because a lateral approach may be performedwithout creating a large incision or stripping muscle from bone, thisapproach does not present the problems associated with a posteriorapproach, namely there is no large incision, muscle stripping, highblood loss, long operating time, or long and painful recovery for thepatient. Furthermore, because a lateral approach to the spine does notinvolve exposing the anterior aspect of the ALL 16, retracting the greatvessels and nearby tissues is unnecessary such that the risks of bloodloss, scar tissue, and sexual dysfunction are much less likely to beencountered.

However, in patients with sagittal imbalance, release of the ALL 16 maybe necessary to achieve the flexibility between the two affectedvertebrae to facilitate insertion of an implant and achieve the amountof correction desired. A need exists for implants, tools, and methodsfor safe and reproducible means of releasing the ALL 16 via lateralapproach as well as restoring the lordotic curvature of the lumbarspine. The present invention is directed at overcoming, or at leastimproving upon, the disadvantages of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many advantages of the present invention will be apparent to thoseskilled in the art with a reading of this specification in conjunctionwith the attached drawings, wherein like reference numerals are appliedto like elements and wherein:

FIG. 1 is a lateral view representing a portion of a sagitallyimbalanced lumbar spine lacking the normal lordotic curvature;

FIG. 2 is a lateral view representing the lumbar spine of FIG. 1 afterrestoration of the lordotic curvature using a hyper-lordotic fusionimplant, according to one example embodiment;

FIG. 3 is a top-down view depicting the creation of a lateral accesscorridor formed with a surgical access system via a lateral approachthrough the side of the patient to the target disc space, according toone example embodiment;

FIG. 4 is a perspective view depicting a lateral access corridor formedwith a retractor assembly through the side of the patient to the targetdisc space, according to one example embodiment;

FIG. 5 is a front perspective view of an anterior longitudinal ligament(ALL) resector for safely releasing the ALL through a lateral accesscorridor, according to one example embodiment;

FIG. 6 is a side view of the ALL resector of FIG. 5;

FIG. 7 is an enlarged side view of the distal end of the ALL resector ofFIG. 5;

FIG. 8 is a side view of an ALL resector for safely releasing the ALLthrough a lateral access corridor, according to another exampleembodiment;

FIG. 9 is an enlarged side view of the distal end of the ALL resector ofFIG. 8;

FIG. 10 is a front perspective view of an ALL resector for safelyreleasing the ALL through a lateral access corridor, according toanother example embodiment;

FIG. 11 is an enlarged perspective view of the distal portion of the ALLresector of FIG. 10;

FIG. 12 is an enlarged side view of the distal portion of the ALLresector of FIG. 10;

FIG. 13 is an exploded front perspective view of the ALL resector ofFIG. 10;

FIG. 14 is a front view of an ALL resector for safely releasing the ALLthrough a lateral access corridor, according to another exampleembodiment;

FIG. 15 is a cross-section front view of the ALL resector of FIG. 14;

FIG. 16 is a perspective view of a bending block for use with the ALLresector of FIG. 14 according to one embodiment;

FIG. 17 is a perspective view of a bending block for use with the ALLresector of FIG. 14 according to a second embodiment;

FIG. 18 is a bottom view of the bending block of FIG. 17;

FIG. 19 is a front perspective view of a hand-held retraction tool foruse with the ALL resector of FIG. 14;

FIG. 20 is a front perspective view of the hand-held retraction tool ofFIG. 19 with an insulative sheath at the tip;

FIG. 21 is a perspective view of an ALL resector for safely releasingthe ALL through a lateral access corridor according to another exampleembodiment;

FIG. 22 is an enlarged perspective view of the distal end of the ALLresector of FIG. 21;

FIG. 23 is a perspective view of a retraction tool for use with the ALLresector of FIG. 21;

FIG. 24 is a posterior side perspective view of a hyper-lordotic implantaccording to a first example embodiment;

FIG. 25 is an anteriorside perspective view of the hyper-lordoticimplant of FIG. 24;

FIG. 26 is a lateral side view of the hyper-lordotic implant of FIG. 24;

FIG. 27 is a posterior side perspective view of a hyper-lordotic implantaccording to a second example embodiment;

FIG. 28 is an anterior side perspective view of the hyper-lordoticimplant of FIG. 27;

FIG. 29 is a lateral side view of the hyper-lordotic implant of FIG. 27;

FIG. 30 is a posterior side perspective view of a hyper-lordotic implantaccording to a third example embodiment;

FIG. 31 is an anterior side perspective view of the hyper-lordoticimplant of FIG. 30;

FIG. 32 is a lateral view of the hyper-lordotic implant of FIG. 30;

FIG. 33 is a posterior side perspective view of a hyper-lordotic implantaccording to a fourth example embodiment;

FIG. 34 is a posterior side perspective view of a hyper-lordotic implantaccording to a fifth example embodiment;

FIG. 35 is another perspective view of the hyper-lordotic implant ofFIG. 34;

FIGS. 36 and 37 are perspective views of an example anchor for securingthe position of the hyper-lordotic implant of FIG. 34;

FIGS. 38 and 39 are perspective views of an example locking element forsecuring the anchor of FIGS. 36 and 37 to the implant of FIG. 34;

FIGS. 40-41 illustrate the locking element of FIG. 38 being engaged tothe anchor of FIGS. 36 and 37;

FIG. 42 is a posterior side perspective view of a hyper-lordotic implantaccording to a sixth example embodiment;

FIG. 43 is an anterior side perspective view of the hyper-lordoticimplant of FIG. 42;

FIG. 44 is a lateral side view of the hyper-lordotic implant of FIG. 42;

FIG. 45 is a perspective view of an example fixation anchor for securingthe position of the hyper-lordotic implant of FIG. 42;

FIG. 46 is an anterior side view of the hyper-lordotic implant of FIG.42 with the fixation anchors of FIG. 45 positioned;

FIG. 47 is posterior side view of the implant and anchors of FIG. 46;

FIG. 48 is a lateral side view of the implant and anchors of FIG. 46;

FIG. 49 is a perspective view of an insertion instrument for implantingthe hyper-lordotic implants, according to one example embodiment;

FIG. 50 is an enlarged perspective view of the distal head of theinsertion instrument of FIG. 49;

FIG. 51 is a perspective view of the insertion instrument of FIG. 49coupled to the hyper-lordotic implant of FIG. 24;

FIG. 52 is a perspective view of a guided clip attachment that can beattached to the insertion instrument of FIG. 49 for guiding theinsertion of the implant along a path defined by the tissue retractorassembly of FIG. 3, according to one example embodiment;

FIG. 53 is an exploded view of the guided clip attachment of FIG. 52;

FIG. 54 is an enlarged view of an attachment base of the guided clipattachment of FIG. 52;

FIG. 55 is a perspective view of the guided clip attachment of FIG. 52coupled to the insertion instrument of FIG. 49 which is coupled to theimplant of FIG. 24;

FIG. 56 is side view of the guided clip attachment of FIG. 52 engagedwith a retractor blade of the tissue retractor assembly of FIG. 3;

FIG. 57 is an enlarged view of the guided clip attachment of FIG. 52engaged with a retractor blade of the tissue retractor assembly of FIG.3;

FIG. 58 is a side view of the guided clip attachment, inserter, andimplant of FIG. 55 engaged with a retractor blade of the tissueretractor assembly of FIG. 3;

FIG. 59 is a perspective view of an inserter instrument with anintegrated attachment clip, according to an embodiment of the presentinvention;

FIG. 60 is a side angle enlarged view of the inserter of FIG. 59 engagedwith a retractor blade of the tissue retractor assembly of FIG. 3;

FIG. 61 is a side angle view of the inserter of FIG. 59 engaged with aretractor blade of the tissue retractor assembly of FIG. 3; and

FIG. 62 is a flow chart indicating the steps utilized to restorelordosis to the spine of a patient, according to one example method.

DETAILED DESCRIPTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The methods and devices described herein include avariety of inventive features and components that warrant patentprotection, both individually and in combination.

With reference to FIGS. 1-2, devices and methods described herein areutilized to correct sagittal imbalance, including lumbar kyphosis, byincreasing the anterior height of the affected spinal area (as opposedto reducing the posterior height, for example via a pedicle subtractionosteotomy). FIG. 1 illustrates a portion of the lumbar spine lacking thestandard lordotic curvature. To correct the sagittal imbalance,illustrated in FIG. 2, a hyper-lordotic implant 10 is positioned intothe disc space at the appropriate spinal level (e.g. between V1 and V2).An anterior sidewall 12 of hyper-lordotic implant 10 has a heightsignificantly larger than an opposing posterior sidewall 14 such thatwhen the implant is positioned within the disc space the anterioraspects of V1 and V2 are forced apart while the posterior aspects arenot (or at least not to the same degree), thus imparting a lordoticcurvature into the spine. To allow the anterior aspects of V1 and V2 toseparate and receive the hyper-lordotic implant 10, the anteriorlongitudinal ligament (ALL) 16 that runs along the anterior aspect ofthe spine may be released or cut 18. Releasing the ALL provides greaterflexibility of movement between the adjacent vertebral bodies, whichallows for a larger height implant and provides greater opportunity toestablish or re-establish a generally normal lordotic curvature in thelumbar region of the spine.

According to a preferred method, the implant 10 is implanted through alateral access corridor formed through the side of the patient.Accessing the targeted spinal site through the lateral access corridoravoids a number of disadvantages associated with posterior access (e.g.cutting through back musculature and possible need to reduce or cut awaypart of the posterior bony structures like lamina, facets, and spinousprocess) and anterior access (e.g. use of an access surgeon to movevarious organs and blood vessels out of the way in order to reach thetarget site). Accordingly, by accessing the target site via a lateralaccess approach and correcting the sagittal imbalance without reducingthe posterior height (i.e. no bone removal) the high blood loss andpainful recovery associated previous methods may be avoided (or at leastmitigated).

According to one example, the lateral access approach to the targetedspinal space may be performed according to the instruments and methodsdescribed in commonly owned U.S. Pat. No. 7,207,949 entitled “SurgicalAccess System and Related Methods,” and/or U.S. Pat. No. 7,905,840entitled “Surgical Access System and Related Methods,” the entirecontents of which are each incorporated herein by reference as if setforth herein in their entireties. With reference to FIGS. 3-4, adiscussion of the lateral access instruments and methods is provided inbrief detail. With the patient 20 positioned on his side, a surgicalaccess system 22 is advanced through an incision 24, into theretroperitoneal space 26, and then through the psoas muscle 28 until thetargeted spinal site (e.g. the disc space between V1 and V2) is reached.The access system 22 may include at least one tissue dilator, andpreferably includes a sequential dilation system 30 with an initialdilator 32 and one or more additional dilators 34 of increasingdiameter, and a tissue retractor assembly 36. As will be appreciated,the initial dilator 32 is preferably advanced to the target site first,and then each of the additional dilators 34 of increasing diameter areadvanced in turn over the previous dilator. A k-wire (not shown) may beadvanced to the target site and docked in place (for example, byinserting the k-wire into the vertebral disc) prior to, in concurrencewith, or after advancing the initial dilator 32 to the target site.

With the sequential dilation system 30 positioned adjacent the targetsite (and optionally docked in place via a k-wire), the retractorassembly 36 is advanced to the target site over the sequential dilationsystem 30. According to the embodiment shown, the retractor assembly 36includes retractor blades 38, 40, 42 and a body 44. With the sequentialdilation system 30 removed, the retractor blades 38, 40, and 42 areseparated (FIG. 4), providing the lateral access corridor through whichinstruments may be advanced to prepare the disc space and insert theimplant 10. According to one example, the posterior blade 38 may befixed in position relative to the spine prior to opening the retractorblades. This may be accomplished, for example by attaching a shim 45 tothe blade 38 (e.g. via track 46 including dove tail grooves 48 formed onthe interior of blade 38) and inserting the distal end of the shim 45into the disc space. In this manner, the posterior blade 38 will notmove posteriorly (towards nerve tissue located in the posterior portionof the psoas muscle 28). Instead, the blades 40 and 42 will move awayfrom the posterior blade 38 to expand the access corridor. Additionally,nerve monitoring (including determining nerve proximity and optionallydirectionality) is performed as at least one component of the accesssystem, and preferably each component of the access system 22 isadvanced through the psoas muscle 28, protecting the delicate nervetissue running through the psoas, as described in the '949 and '840patents. Monitoring the proximity of nerves also allows the posteriorblade 38 of the retractor assembly 36 to be positioned very posterior(all the way back to the exiting nerve roots), thus exposing a greaterportion of the disc space than would otherwise be safely achievable.This in turn permits full removal of the disc and implantation of animplant with a wider footprint implant. Use of a wider footprintmeanwhile makes utilization of a hyper-lordotic implant with a largelordotic angle (e.g. between 20-40 degrees) more practical.

With the lateral access corridor formed (as pictured in FIG. 4) thetarget site may be prepped for insertion of the implant 10. Preparationof the disc space may include performing an annulotomy, removal of discmaterial, and abrasion of the endplates. Instruments such as annulotomyknives, pituitaries, curettes, disc cutters, endplate scrapers may beused during disc preparation. Additionally, as discussed above, it maybe necessary to release the ALL 16 in order to create enough flexibilitybetween the adjacent vertebrae (e.g. V1 and V2) to receive thehyper-lordotic implant 10. Unlike an anterior approach (where the greatvessels and other tissue lying anterior to the disc space are retractedduring the approach), when the target disc is approached laterally, thegreat vessels remain adjacent to the ALL along the anterior face of thespine. Thus, while cutting the ALL is generally simple and necessaryduring an anterior approach surgery, cutting the ALL during a lateralapproach surgery has typically been unnecessary and can be difficultbecause of the need to avoid damaging the great vessels. Accordingly,FIGS. 5-23 set forth various example embodiments of ALL resectinginstruments for safely releasing the ALL from a lateral approach.

FIGS. 5-7 illustrate an example embodiment of an ALL resector 50. By wayof example only, the ALL resector 50 can be used to release (by way ofcutting) the ALL anterior to the operative disc space in surgeriesrequiring a large degree of curvature correction (for example, greaterthan 15 degrees). The ALL resector 50 includes a handle 52 (for example,a T-handle) located at the proximal end of the elongated shaft 54 and adistal head 56 for resecting the ALL 16. The distal head 56 includesdistally extending first and second fingers 58, 60, which form anopening 62 therebetween. First and second tapered surfaces 64, 66 whichextend a distance from the elongated shaft 54 along the fingers 58, 60enable the distal head 56 to insert gently between tissue. As best shownin FIG. 7, the first finger 58 may be shorter in length than the secondfinger 60. This may serve a variety of purposes, which include givingthe user greater viewing capabilities of the cutting area due to ashorter first finger 58 while providing greater protection and insertionguidance with a longer second finger 60. However, the first and secondfinger 58, 60 may be provided in any number of length configurationswithout departing from the scope of the present invention. By way ofexample, it has been contemplated that the first finger 58 may becompletely removed. Alternatively the fingers may be curved (asillustrated in the embodiment depicted in FIGS. 8-9) and have a moresubstantial width than shown in FIGS. 5-7. Curvature of the first andsecond fingers may allow the distal head 56 to follow closely along theanterior side of the spine and/or along a curved spatula (not shown)positioned adjacent the anterior side of the vertebral body. Though notshown, a user may optionally insert a spatula along the anterior portionof the ALL 16 prior to inserting the ALL retractor 50. The spatula mayserve as additional protection between the delicate tissue anterior tothe ALL and the cutting blade 68 of the ALL resector 50. With a spatulain place the user may insert the distal head 56 such that it approachesthe lateral side of the ALL 16 and is guided along the inside edge ofthe spatula. By way of example, the spatula may be straight or curved tomatch the selected fingers of the distal head 56.

A cutting blade 68 is exposed between the first and second fingers 58,60 in the opening 62. A slot 70 formed along a side of the distal head56 allows a cutting blade 68 to be inserted and removed from the distalhead 56 as needed (such as, for example, if a blade were to become dullor bent). Thus, the cutting blade 68 may be disposable and the remainderof the ALL resector 50 may be reusable. Alternatively, both cuttingblade 68 and remainder of the ALL resector 50 may be reusable or bothmay be disposable. In use, the ALL resector 50 is preferably positionedsuch that the second finger 60 is aligned along the anterior side of theALL and the first finger 58 is aligned along the posterior side of theALL 16, thus, at least partially bounding the ALL 16 on either sidewhich allows the cutting blade 68 to maintain a generally perpendicularalignment relative to the length of the ALL 16. The ALL resector 50 isadvanced forward so that the cutting blade 70 cuts through the ALL 16from one lateral edge to the other. As discussed above, the secondfinger 60 is preferably aligned along the anterior side of the ALL 16 asthe distal head 56 is advanced, thereby shielding the tissue lyinganterior to the finger 60 (e.g. great vessels, etc. . . . ) from thecutting blade 68. Furthermore, as the user advances the ALL resector 50,the fingers 58, 60 may also act as a stabilizing guide.

FIGS. 8-9 illustrate an ALL resector 72 according to a second exampleembodiment. The ALL resector 72 differs from the ALL resector 50 in thatits first and second fingers 74, 76 are generally curved. The remainderof the features and functions of the ALL resector 72 are essentially thesame as the features and functions of the ALL resector 50 such that theywill not be repeated here. The curvature of the first and second fingers74, 76 allow the distal head 56 to follow closely along the anterioraspect of the spine. By way of example, the curvature of the secondfinger 76 allows the distal head 56 to more easily slide along a curvedspatula (not shown) positioned adjacent to the anterior aspect of thevertebral body. Both the curved spatula and first and second fingers 74,76 are curved to generally mimic the curvature of the anterior aspect ofthe spine. This enables a surgeon to more easily maneuver the distalhead 56 while cutting across the ALL 16.

Additionally, it has been contemplated that the first and second fingers74, 76 be sized and shaped to have a greater width than the first andsecond fingers 58, 60 of ALL resector 50. Added width of the fingers mayprovide for increased protection and shielding of the cutting area whileadding greater stability during insertion.

FIGS. 10-13 illustrate an ALL resector 78 according to a third exampleembodiment. The ALL resector 78 includes a tissue retractor 80 and asliding blade 82 which function to both cut the ALL 16 and protectsurrounding tissue, blood vessels, and nerves from unwanted damage(similar to the previous embodiments discussed above with reference toALL resectors 50 and 72). The tissue retractor 80 includes a handle 84,hollow shaft 86, and head 88. The head 88 is curved, preferably suchthat the inside surface 90 complements the curvature of the anterioraspects of the spinal target site. The head 88 may thus be positionedthrough the lateral access corridor to the spine and such that thecurved interior surface 90 nestles around the curved anterior aspect ofthe spine. The outside surface 92 will form a barrier, protecting tissuealong the anterior spine from inadvertent contact with the sliding bladewhen the ALL 16 is cut. Furthermore, the tissue retractor 80 can befurther manipulated to move tissue and further expose the anterioraspect of the target site. The hollow shaft 86 includes a central lumen94 with an opening adjacent the head 88 and another opening at theopposing end such that the sliding blade 82 may travel through the shaft86.

The sliding blade 82 includes a blade 96 that is secured to the distalend of an extender 98 by way of an attachment feature 100. Theattachment feature 100 as shown is similar to known attachment featuresused for attaching a blade at the end of a scalpel. It will beappreciated that any number of mechanisms may be used to attach blade 96to extender 98. Blade 96 may be disposable and extender 98 may bereusable. Alternatively, both blade 96 and extender 100 may be reusableor both may be disposable. The blade 96 includes a cutting edge 102that, when advanced beyond the lumen 94 of shaft 86, cuts through tissueor material situated adjacent the cutting edge 102.

The proximal end of the extender 98 includes a grip 104 that a surgeonor other user may use to manipulate the position of the sliding blade 82relative to the shaft 86 and head 88. At least one stop feature 106extends from the outer surface of the extender 98 which engages with atrack 108 that extends along a portion of the elongated shaft 86. Thetrack 108 limits the longitudinal travel of the sliding blade 82relative to the shaft 86 so that the sliding blade 82 remains slidablymated to the tissue retractor 80 without becoming unassembled and suchthat the blade 96 cannot extend beyond the protective head 88.Additionally, the stop feature 106 restricts rotation of the slidingblade 82 relative to the tissue retractor 80.

FIGS. 14-20 illustrate an ALL resector 110 according to a fourth exampleembodiment. As shown in FIGS. 14-15, the ALL resector 110 is comprisedof a handle 112, a conductive shaft 114, a bendable region 116, an anodetip 118, and an electrical connector (not shown).

Preferably, the conductive shaft 114 is coated with an insulativecoating 118 about its exterior surface. In some embodiments, thebendable region 116 may be generally hook-shaped 120 such that the anodetip 118 would be oriented in an optimal angle for resecting the ALL 16from the lateral approach. Alternatively, the bendable region 116 may begenerally straight in shape such that customizable bending may beachieved as will be described below.

FIG. 16 illustrates a bending block system 122 according to one exampleembodiment for bending the bendable region 116 of the ALL resector 110.Bending block 122 may be generally square or rectangle-shaped and iscomprised of a handle 126 and one or more bending slot 128. The bendingslots 128 may be of different lengths such that the bendable region 116of the ALL resector 110 may be placed in a bending slot 128 and thenbent to an appropriate angle for cutting based in part uponconsiderations of surgeon preference as well as patient anatomy. FIGS.17-18 illustrate a bending block system 124 according to a secondexample embodiment. Bending block 124 may be generally circular in shapeand comprised of a handle 126 and one or more bending slots 128. Similarto the previous embodiment, the bending slots 128 may be of differentlengths such that the bendable region 116 of the ALL resector 110 may beplaced in a bending slot 128 and then bent to an appropriate angle forcutting based in part upon surgeon preference as well as patient anatomyrestrictions.

The ALL resector 110 is preferably compatible with a hand-heldretraction tool, for example the hand-held retraction tool 130 of FIG.19. The retraction tool 130 is comprised of a handle 132, a shaft 134,and a paddle 136. The paddle 136 may be bent or straight such that it isable to separate and form a barrier between the great vessels and theALL resector 110. Preferably, the retraction tool 130 is non-conductive.This may be accomplished by constructing the retraction tool 130 ofnon-conductive material or by coating the surfaces of the retractiontool with an insulating material. According to one example, the paddle136 is rigid enough to achieve retract the great vessels withoutyielding under the weight of the vessels. According to another example,the paddle 136 may be flexible such that it can be inserted under thegreat vessels and flex up as the ALL resector 110 is advanced underneaththe paddle 136 to cut the ALL. As shown in FIG. 20, a protective sheath138 may surround the paddle 136 of the retraction tool 130 for addedprotection when the paddle 136 contacts the great vessels.

To use the ALL resector 110, the surgeon may preferably first insert theretraction tool 130 between the ALL 16 and the great vessels, aligningthe paddle 136 in a manner that protects the vessels withoutover-retracting them. The surgeon determines the ideal angle to approachthe ALL 16 and whether to use a hooked, straight, or custom-bent tip.Once the ALL resector 110 is prepared with the preferred tip 118, theelectrical connector can be connected to an electrosurgical unit thatdelivers electrical current to the anode tip 118 in an amount that willcauterize (thus cut) the tissue of the ALL. The non-conductive paddle136 of the retraction tool 130 protects the great vessels from thecauterizing effect of the electrical current.

FIGS. 21-23 illustrate yet ALL resector 142 according to a fifth exampleembodiment.

The ALL resector 142 includes a tissue retractor component 144 and acutter component 146 which work in concert to cut the ALL and protectsurrounding tissue, blood vessels, and nerves from unwanted damage(similar to the other ALL resector embodiments discussed above). Thetissue retractor 144 protects against anterior migration of the cutter146 towards the great vessels and includes a handle 148, an elongateshaft 150, and a head 152. The head 152 is curved, preferably in such away that the inside surface 154 compliments the curvature of theanterior aspects of the spinal target site. The head 152 may thus bepositioned through the lateral access corridor to the spine such thatthe curved interior surface 154 nestles around the curved anterioraspect of the spine. The outside surface 156 will form a barrier,protecting tissue along the anterior spine from inadvertent contact withthe cutting edge 166 of the cutter 146 when the ALL 16 is cut.Furthermore, the tissue retractor 144 can be further manipulated to movetissue and further expose the anterior aspect of the target site. Theelongate shaft 150 includes two guide posts 158 that are sized anddimensioned to function as a track to allow the cutter 146 to travelbetween the guide posts 158 and along the length of the elongate shaft150 as will be described below.

The cutter 146 includes a blade 160 that is secured to the distal end ofan extender 162 by way of an attachment feature 164. The attachmentfeature 164 as shown is similar to known attachment features used forattaching a cutting blade at the end of a scalpel. In the embodimentshown, the blade 160 includes only a single cutting edge 166, however itis contemplated that more than one cutting edge 166 may be utilized. Itwill be appreciated that any number of mechanisms may be used to attachblade 160 to extender 162. Blade 160 may be disposable and extender 162may be reusable. Alternatively, both blade 160 and extender 162 may bereusable or both may be disposable. The blade 160 includes a cuttingedge 166 that, when advanced along the elongate shaft 150 of theretractor component 144, cuts through tissue or material situatedadjacent the cutting edge 166.

The proximal end of the extender 162 includes a connector 168 to which ahandle may be connected that a surgeon may use to manipulate theposition of the cutter 146 relative to the shaft 150 and head 152. Atleast one anti-rotation bar 170 extends from the outer surface of theextender 162 which can be slidably inserted between guide posts 158 andtravel along a portion of the elongated shaft 150. When the cutter 146is positioned with the anti-rotation bar 170 between the guide posts158, the guide posts 158 keeps the cutter 146 slidably mated to thetissue retractor 144 and restricts rotation of the cutter 146 relativeto the tissue retractor 144. Further, the cutter 146 is restricted frommovement in the cephalad/caudal direction by the vertebral bodies V1 andV2. Additionally, the extender 162 includes a pair of distal wings 172protruding generally perpendicularly from the outer surface of theextender 162. Distal wings 172 are sized and dimensioned to contact theproximal surfaces of V1 and V2 when the blade 160 is fully advancedacross the ALL in order to act as a depth stop and restrict excessiveadvancement of the cutting blade 160. The cutting blade 160 may also beprovided with an elongated finger 174 as shown in FIG. 22, that may beused for further protection of nearby tissue (for example, the posteriorlongitudinal ligament or the great vessels) and as stabilizer duringuse.

While the ALL resectors 50, 72, 78, 110,142 are susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and are herein described indetail. It should be understood, however, that the description herein ofspecific embodiments is not intended to limit the invention to theparticular forms disclosed, but on the contrary, the invention is tocover all modifications, equivalents, and alternatives falling withinthe scope and spirit of the invention as defined herein. Furthermore,the ALL resectors 50, 72, 78, 110, 142 may be incorporated into asurgical kit or used with any number of various tooling and/or implants.The following are examples of tooling and implants that may be used inconjunction with the ALL resectors discussed herein, as well as anyvariation of an ALL resector not disclosed herein.

As discussed above, a patient may undergo a lateral procedure and havean intervertebral disc space prepared for the permanent implantation of,for example, a hyperlordotic implant. The intervertebral space may beprepared via any number of well-known surgical preparation tools,including but not limited to, kerrisons, rongeurs, pituitaries, andrasps. Preparation of the disc space may also include the removal of anyimplants already occupying the disc space. By way of example only,during a revision surgery, it may be necessary to remove a spinal fusionimplant or TDR device previously implanted.

Once the disc space is prepared, the surgeon may designate theappropriate implant size. This may be accomplished through the use of atrial sizer (not shown). The trial sizer may include grooves along atleast a portion of the upper and/or lower surfaces to help insert thesizer along the desired path through the intervertebral space. The sizermay also be connected to a guide clip attachment that can be guidedalong the retractor blade 38 of the retractor assembly (as will bedescribed below in connection with the implant insertion). When theappropriate size is determined, an insertion instrument, for example,insertion instrument 310 may then be secured to an implant such that theimplant is advanceable into the prepared intervertebral disc space.

Turning now to FIGS. 24-48, various embodiments of a hyper-lordoticimplant for insertion through a lateral approach are described. FIGS.24-26, for example, illustrate an implant 200 according to a firstembodiment. Implant 200 may preferably be comprised of any suitablenon-bone composition having suitable radiolucent characteristics,including but not limited to polymer compositions (e.g.poly-ether-ether-ketone (PEEK) and/or poly-ether-ketone-ketone (PEKK))or any combination of PEEK and PEKK. Other materials such as forexample, metal, ceramics, and bone may also be utilized for the implant200. Implant 200 has a top surface 202 and bottom surface 204 forcontacting V1 and V2, anterior sidewall 206, posterior sidewall 208, andfront or leading side 210, and rear or trailing side 212. As discussed,the anterior sidewall 206 has a height greater than the posteriorsidewall 208 such that the top surface 202 and bottom surface 204converge towards each other in the posterior direction. As shown in FIG.27, the angle of convergence is represented by a. By way of example, thetop and bottom surfaces may converge at an angle between 20 and 40degrees. It is contemplated that variations of the implant 200 may besimultaneously provided such that the user may select from differentavailable ranges. For example, variations may be provided with 20degree, 30 degree, and 40 degree angles. The top and bottom surfaces maybe planar or provided as convex to better match the natural contours ofthe vertebral end plates. The top surface 202 and the bottom surface 204may be interchangeable (i.e. the implant may be flipped) such that thesame implant may be implanted from either the left or right side of thepatient.

The implant 200 may be provided with any number of additional featuresfor promoting fusion, such as fusion apertures 214 extending between thetop and bottom surfaces 202, 204 which allow a boney bridge to formthrough the implant 200. Various osteoinductive materials may bedeposited within the apertures 214 and/or adjacent to the implant 200 tofurther facilitate fusion. Such osteoinductive materials may beintroduced before, during, or after the insertion of the exemplaryspinal fusion implant 200, and may include (but are not necessarilylimited to) autologous bone harvested from the patient receiving thespinal fusion implant, bone allograft, bone xenograft, any number ofnon-bone implants (e.g. ceramic, metallic, polymer), bone morphogenicprotein, and bio-resorbable compositions, including but not limited toany of a variety of poly (D,L-lactide-co-glycolide) based polymers.Visualization apertures 216 situated along the sidewalls, may aid invisualization at the time of implantation and at subsequent clinicalevaluations. More specifically, based on the generally radiolucentnature of the preferred embodiment of implant 200, the visualizationapertures 216 provide the ability to visualize the interior of theimplant 200 during X-ray and/or other imaging techniques. Further, thevisualization apertures 216 will provide an avenue for cellularmigration to the exterior of the implant 200. Thus the implant 200 willserve as additional scaffolding for bone fusion on the exterior of theimplant 200.

The spinal fusion implant 200 may be provided in any number of sizes byvarying one or more of the implant height, width, and length. The lengthof the implant 200 is such that it may span from one lateral aspect ofthe disc space to the other, engaging the apophyseal ring on each side.By way of example, the implant 200 may be provided with a length between40 mm and 60 mm. The size ranges described are generally appropriate forimplantation into the lordotic lumbar portion of the spine. Thedimensions of the implant 200 may be altered according to proportions ofthe particular patient. Further, variation of the implant dimensions maybe implemented to produce implants generally appropriate forimplantation into any portion of the spine. By way of example only, theposterior sidewall 208 may be dimensioned at a height greater than thatof anterior sidewall 206 such that top surface 202 and bottom surface204 converge toward one another at the anterior sidewall 206 (e.g. tocreate a hyper-kyphotic implant) in order to promote the proper kyphoticangle in the thoracic spine.

As shown in FIGS. 24-25, the implant 200 may include anti-migrationfeatures designed to increase the friction between the spinal fusionimplant 200 and the adjacent contact surfaces of the vertebral bodies,and thereby minimize movement or slippage of the implant 200 afterimplantation. Such anti-migration features may include ridges 220provided along the top surface 202 and/or bottom surface 204. Additionalanti-migration features may also include spike elements 222 disposedalong the top 202 and bottom surfaces 204. The spike elements 222 may bemanufactured from any of a variety of suitable materials, including butnot limited to, a metal, ceramic, and/or polymer material, preferablyhaving radiopaque characteristics. The spike elements 222 may eachcomprise a unitary element extending through the top surface 202 andbottom surface 204. Alternatively, each spike element 222 may comprise ashorter element which only extends to a single surface. In any event,when the spike elements 222 are provided having radiodensecharacteristics, and the implant 200 is manufactured from a radiolucentmaterial (such as, by way of example only, PEEK or PEKK), the spikeelements 222 will be readily observable under X-ray or fluoroscopy suchthat a surgeon may track the progress of the implant 200 duringimplantation and/or the placement of the implant 200 after implantation.

Tapered surfaces 224 may be provide along the leading end 210 to helpfacilitate insertion of the implant 200. Additional instrumentation mayalso be used to help deploy the implant 200 into the disc space. By wayof example, the implant installation device shown and described indetail in the commonly owned and copending U.S. patent application Ser.No. 12/378,685, entitled “Implant Installation Assembly and RelatedMethods,” filed on Feb. 17, 2009, the entire contents of which isincorporated by reference herein, may be used to help distract the discspace and deposit the implant therein.

The spinal fusion implant 200 may be provided with any number ofsuitable features for engaging the insertion instrument 310 (illustratedin FIG. 49). As best viewed in FIG. 24, one such engagement mechanisminvolves a threaded receiving aperture 226 in the posterior sidewall 208of the implant 200. The threaded receiving aperture 226 is dimensionedto threadably receive a threaded connector 182 on the insertioninstrument 310. In addition to the receiving aperture 226, the implant200 is preferably equipped with a pair of grooved purchase regions 228extending either generally vertically or generally horizontally fromeither side of the receiving aperture 226. The grooved purchase regions228 are dimensioned to receive corresponding distal head plates 326 onthe insertion instrument 310. Together, these engagement mechanismsprovide an enhanced engagement between the implant 200 and insertioninstrument 310 and prevent unwanted rotation of the implant 200 duringinsertion as will be described in greater detail below. Having beendeposited in the disc space, the implant 200 facilitates spinal fusionover time by maintaining the restored curvature as natural bone growthoccurs through and/or past the implant 200, resulting in the formationof a boney bridge extending between the adjacent vertebral bodies V1 andV2.

FIGS. 27-29 illustrate an implant 230 according to a second exampleembodiment of a hyper-lordotic implant. The implant 230 shares manysimilar features with the implant 200 such that repeat discussion in notnecessary. The implant 230 differs from the implant 200 in that atrailing side 212 is configured for fixed engagement to one of theadjacent vertebral bodies (i.e. V1 or V2) to supplement theanti-migration features and ensure the hyper-lordotic implant is notprojected out of the disc space. Specifically, the implant 230 includesa tab 232 extending vertically above the top surface 202 and below thebottom surface 204.

In the example shown, the tab 232 is arcuate at the corners andgenerally trapezoidal, however, it should be appreciated that the tab232 may take any number of suitable shapes, such as, by way of exampleonly, square, rectangular, triangular, partially circular, or partiallyovular, among others, the tab may be of different lengths. It shouldalso be appreciated that tab 232 surfaces may be one or more ofgenerally concave, generally convex, or generally planar. The tab 232 iscomprised of a perimeter surface 234, an anterior side 236, a posteriorside 238, and a tab side 240. Anterior side 236 and posterior side 238may be interchangeable (i.e. the implant may be flipped horizontally orvertically) such that the same implant may be implanted from either theright side or the left side of the patient. Anterior side 236 andposterior side 238 are preferably, though not necessarily, configuredcoplanar with anterior sidewall 206 and posterior sidewall 208,respectively (i.e. the width of tab 232 is preferably equal to the widthof the implant proximal end, however, the width of the tab may begreater than, or less than, the width of the implant at proximal end).Tab side 240 of tab 232 is configured to engage the exterior surface ofan adjacent vertebrae.

The tab 232 is provided with a fixation aperture 242 for enabling theengagement of a fixation anchor 302 within the vertebral bone to securethe placement of the implant 230. The fixation aperture 242 may have anynumber of shapes and/or features for enabling an anchor (for example thefixation anchor 302 of FIG. 45) to engage and secure the positioning ofan implant 230. The anchor engages within the vertebral bone through thefixation aperture 242 to secure the placement of the implant 230. Inuse, when the implant 230 is positioned within the disc space, the tab232 engages the exterior of the upper and lower vertebra and the anchor302 may be driven into the side of either the upper or lower vertebra,depending on the orientation of the implant 230. One will appreciatethat various locking mechanisms may be utilized and positioned over orwithin the fixation aperture 234 to prevent the anchor 302 from unwanteddisengagement with the implant 230. For example, a suitable lockingmechanism may be in the form of a canted coil disposed within thefixation aperture 234 (as illustrated in FIG. 42), or may be engaged tothe trailing end 212 and cover all or a portion of the fixation aperture242 after the anchor 302 is positioned.

FIGS. 30-32 illustrate an implant 248 according to a third exampleembodiment of a hyper-lordotic implant. The implant 248 shares manysimilar features with the implants 200 and 230 such that repeatdiscussion of them all is not necessary. The implant 248 differs fromthe implant 230 in that the tab 249 extends higher (or lower dependingon the insertion orientation) from the surface of the implant and solelyin one direction such that it only engages the exterior of the upper (orlower) vertebra and the tab 249 has a partially ovular shape where itextends from the implant. Any number of features to prevent the backingout of an anchor may be utilized with this embodiment.

FIG. 33 illustrates a implant 250 according to a fourth exampleembodiment a hyper-lordotic implant. The implant 248 shares many similarfeatures with the implants 200, 230, and 248 such that repeat discussionof them all is not necessary. The implant 250 differs from the previousembodiments in that it is configured for fixation to one of the adjacentvertebrae but does not utilize a tab or tabs to do so. Instead, theimplant 250 has one or more fixation apertures 252 that travel throughthe body of the implant 250. The fixation apertures 252 are formed at anangle from a side of the implant such that the anchors will travelthrough the fixation apertures 252 into the vertebral bodies through thevertebral endplate. Any number of features to prevent the backing out ofan anchor may be utilized with this embodiment.

FIGS. 34-41 illustrate a an implant 260 according to a fifth exampleembodiment of a hyper-lordotic implant. The features and functions areessentially the same as the features and functions described=withreference to the implants 230, 248, and 250 such that they will not berepeated here. However, spinal fusion implant differs from the implantsdescribed above in that fixation apertures 261 are configured forengagement with anchors 262 that are anchored into the vertebral bodiesbefore the implant 260 is implanted. FIGS. 36-37 illustrate an exampleof an anchor 262 specially for use with the implant 260. The anchor 260is designed to be implanted prior to the implant 260. The anchor 262includes a head 266 at its proximal end, an intermediate region 268, andan elongated shaft 270 extending distally from the intermediate region268. The head 266 has a generally cylindrical shape and extendsgenerally perpendicularly in proximal direction from the top of theintermediate region 268. The head 266 includes an exterior threadform272 configured to engage the locking element 274. In use, the anchor 262is placed first, and the fixation aperture 261 is fitted over the head266. The head 266 further includes a recess 276 for receiving a portionof an instrument for insertion (for example, a driver). The recess 276may have any shape that corresponds to the shape of the distal tip ofthe driver.

The intermediate region 268 includes a plurality of vertically-orientedchocks 264 distributed in a radial gear-shaped pattern about the anchor262. The chocks 264 are configured to engage with the contouredperiphery 263 of a fixation aperture 252 to provide a solid connectionbetween the anchor 262 and implant 260. The intermediate region 268further has a sloped distal-facing surface 278 configured to contact therelevant vertebral bodies. The sloped distal-facing surface 278 may haveany cross-sectional shape desired by the user, including but not limitedto concave, convex, and generally planar.

The elongated shaft 270 extends distally from the intermediate region268. The shaft 270 includes a threadform 280 configured to providepurchase into the bone. By way of example only, the threadform 280 isprovided as a single-lead threadform, however, multiple threads may beused without departing from the scope of the present invention. Theshaft 270 further includes a notch 282 to provide the anchor 262 with aself-tapping feature. Further, the anchor 262 may be provided with alumen 284 extending therethrough such that the anchor 262 is cannulated.The anchor 262 has a major diameter defined by the outer diameter of thethreadform 272.

FIGS. 38-39 illustrate an example of a locking element 274 for use withthe anchor 262. The locking element 274 includes a central aperture 286sized and configured to receive the head 266 of the anchor 262 therein.To facilitate this arrangement, the central aperture 286 is providedwith a threadform 288 that complements the thread 272 of the head 266.The upper exterior portion 290 is configured to engage the distal end ofan insertion device (for example, an inserter). As best seen in FIG. 38,the upper exterior portion 290 has a generally sunburst-shapedcross-section, with a plurality of radial protrusions 292 separated by aplurality of recesses 294.

FIGS. 40-41 illustrate the engagement of the locking element 274 withthe anchor 262. To achieve this, the locking element 274 is advancedonto the head 266 of the anchor 262 which extends out of the fixationaperture 242 of the implant 260. The thread 288 of the locking element274 cooperates with the head 266 to create a threaded engagement. Thelocking element 274 may then be rotated in a clockwise direction toadvance the locking element 274 onto the head of the anchor 266.Rotation in a counterclockwise direction could cause the locking element274 to retreat up into the head 266, allowing for disengagement andremoval if necessary.

FIGS. 42-48 illustrate an implant 300 according to a sixth exampleembodiment of a hyper-lordotic implant. The implant 300 shares manysimilar features with the implants 200, 230, 248, 250, and 260 such thatrepeat discussion is not necessary. The implant 300 differs from theimplants embodiments described above in that implant is configured forfixed engagement to each or the adjacent vertebral bodies (i.e. V1 andV2). Specifically, the implant 300 includes a tab 304 extendingvertically above the top surface of the implant and a second tab 304extending below the bottom surface of the implant. Each tab 304 includesa fixation aperture 305 for receiving a fixation anchor 302 therethroughto for anchoring into the vertebral bone to secure the placement of theimplant. In use, when the implant 300 is positioned within the discspace, the tabs 304 engage the exterior of the upper and lower vertebraand a fixation anchor 302 is driven into the side of each of the upperor lower vertebra. A locking element in the form of a canted coil 306 isalso depicted. The canted coil 306 resides in a groove formed within thefixation aperture. A ridge 308 on the head of the anchor 302 has atapered lower surface and a generally flat upper surface such that theinner diameter of the canted coil 306 expands, due to engagement withthe tapered surface of the ridge 308 as the anchor is advanced, allowingthe anchor to pass. When the ridge 308 advances past the canted coil 306the inner diameter of the coil returns to the original dimension,preventing the anchor from backing out of the fixation aperture 305.

The hyper-lordotic implants 200, 230, 248, 250, 260, and 300 have beenshown, by way of example, according to a number of embodiments. Itshould be understood, however, that the description herein of specificembodiments is not intended to limit the scope to the particular formsdisclosed, but on the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the scopeand spirit of the invention as defined herein. By way of example, onewill appreciate that the various quantities, sizes, shapes and lockingelements/anchors of the tabs described for fixing the implants to thespine, as well as additional possible quantities, sizes, shapes andlocking mechanisms/anchors not described, may be combined in any numberof different configurations that can provide for a hyper-lordoticimplant that can be fixed in position relative to the spine.

With reference to FIG. 49-51, an exemplary insertion instrument 310 is adescribed. The insertion instrument 310 includes a handle 312, athumbwheel housing 314, an elongate tubular element 316, an insertershaft (not shown), and a distal inserter head 318.

The handle 312 is generally disposed at the proximal end of theinsertion instrument 310. The handle 312 may be further equipped with auniversal connector to allow the attachment of accessories for ease ofhandling of the insertion instrument 310 (e.g. a straight handle or aT-handle, not shown). The handle 312 is fixed to the thumbwheel housing314 allowing easy handling by the user. By way of example, thethumbwheel housing 314 holds at least one thumbwheel 320, and at leastone spacer (not shown). Because the handle 312 is fixed, the user haseasy access to the thumbwheel 320 and can stably turn the thumbwheel 320relative to the thumbwheel housing 314. Additionally, the relativeorientation of the thumbwheel 320 to the handle 312 orients the userwith respect to the distal insertion head 318. The inserter shaft (notshown) is attached to the thumbwheel 320 and is freely rotatable withlow friction due to the spacer. The user may then employ the thumbwheelto rotate the inserter shaft thereby advancing it towards the distalinserter head 318.

The elongate tubular element 316 is generally cylindrical and of alength sufficient to allow the device to span from the surgical targetsite to a location sufficiently outside the patient's body so the handle312 and thumbwheel housing 314 can be easily accessed by a surgeon or acomplimentary controlling device. The elongate tubular element 316 isdimensioned to receive a spring (not shown) and the proximal end of theinserter shaft into the inner bore 322 of the elongate tubular element316. The elongate tubular element 316 is further configured to be snuglyreceived within the inner recess 336 of the snap-fit channel 330 of theguided clip attachment 338 which will be explained in further detailbelow. The distal inserter head 318 is comprised of a threaded connector324 and a plate 326. The threaded connector 324 is sized and dimensionedto be threadably received by the receiving aperture 104. Further, theplate 326 is sized and dimensioned to be snugly received within thegrooved purchase region 106.

According to one example the insertion instrument 310 may be used incombination with a guided clip attachment 328 that engages a retractorblade 38 of the retractor assembly 36 to facilitating proper orientationand positioning of a hyper-lordotic implant, for example hyper-lordoticimplant 200 as shown, or any of the various hyper-lordotic implantembodiments described herein. As illustrated in FIGS. 52-54, the guidedclip attachment 328 includes a snap-fit channel 330, a locking element332, and an attachment base 334. The snap-fit channel 330 contains aninner recess 336 that is generally arch-shaped and is sized anddimensioned to snugly receive at least a portion of the length of theelongate tubular element 316 of the insertion instrument 310. Thesnap-fit channel 330 may also be provided with at least one aperture 338for receiving a ball 346 from the locking element 332 as will bedescribed in greater detail below. The locking element 332 may becomprised of any suitable mechanism for restricting movement of theinserter instrument 310 relative to the guided clip attachment 328,including but not limited to the ball detent mechanism described. Asdepicted in FIG. 52, the locking mechanism may preferably include aslide lock having a sliding bar 340 with locking rod extensions 342extending therefrom on either side. The rod extensions 342 each includea detent 343 situated along a portion of the rod extension 342. Thelocking rod extensions 342 are situated in and slidable within an innergroove 344 of the locking element 332. In the unlocked position thedetents 345 align with the balls 346 such that the balls 346 may bedepressed into the detents 345 (such that they do not extend into thechannel 330) as the tubular element 316 of the insertion instrument 310passes the balls 346 during insertion into the channel 330. In thelocked position the balls 346 do not align with the detents 345 and thuscannot be depressed fully into the ball apertures. The balls 346 thusprotrude into the channel 330 over the tubular body 316, preventingremoval of the tubular body 316.

In addition to the locking mechanism 332, one or more ball plungers 348may also be provided within the snap-fit channel 330 to provide greaterstability and control of the guided clip attachment 328 relative to theinsertion instrument 310. The ball plunger 348 may be further providedwith a threaded screw 350 surrounding it, thereby creating aspring-loaded ball detent mechanism. The ball-plunger components 348,350 are disposed within, and protrude from, at least one aperture 352located on the inner recess 336 of the guided clip attachment 328. Whenthe guided clip attachment 328 is attached to the elongate tubularelement 316 of the inserter instrument 310, the spring-loaded ballcomponents 348, 350 retract into the aperture 352 to allow the elongatetubular element 316 to be fully captured while still providing frictionbetween the guided clip attachment 328 and the elongate tubular element316 portion of the insertion instrument 310.

The guided clip attachment 328 further includes an attachment base 334for coupling with a retractor blade (e.g. retractor blades, 38, 40, or42) as will be explained below. This attachment provides stability forthe implant 200 to be inserted and to prevent the implant 200 frommigrating anteriorly during insertion. The attachment base 334 iscomprised of a shim 354 and a stabilizing arm 356. The shim 354 iscapable of rotating in two axes via an internal polyaxial joint 358 thatallows for cephalad-caudal and anterior-posterior positioning of theimplant 328. Further, the stabilizing arm 356 contains cut-out regions362 to limit the amount of rotation in the cephalad-caudal directions.The cut-out regions 362 may be sized and figured to allow for anypre-determined amount of rotation between 1 and 359 degrees. Accordingto one example, the cut-outs are configured to allow for rotation withinthe range of 10 to 30 degrees. Steps 360 engage the ends of the cutoutregion to prevent further rotation and also rest against the stabilizingarm 356 to prevent lateral rocking of the shim. Alternatively, cutoutregions 362 may be removed and the shim may be allowed to rotate 360degrees. The shim 354 has at least one notch 364 that is sized anddimensioned to snugly mate with the track 46 (specifically the dove tailgrooves 48 formed on the interior of retractor blade 42) and may travelup and down the length of the retractor blade 38.

According to another example embodiment depicted in FIGS. 59-61, aninserter instrument 370 that is similar to the inserter 310 except thatit is equipped with an integrated guide clip 372 is provided. Like theguided clip attachment 328, the guide clip 372, As the guided clip 372provides additional stability and positioning assistance duringinsertion of the implant. The guide clip 372 includes a shim 374 and astabilizing arm 376. The shim 354 is capable of rotating in two axes viaan internal polyaxial joint (not shown) that allows for cephalad-caudaland anterior-posterior positioning of the implant. The stabilizing arm376 may contain cut-out regions 378 to limit the amount of rotation inthe cephalad-caudal directions. The cut-out regions 378 may be sized andfigured to allow for any pre-determined amount of rotation between 1 and359 degrees. According to one example, the cut-outs are configured toallow for rotation within the range of 10 to 30 degrees. Steps 380engage the ends of the cutout region to prevent further rotation andalso rest against the stabilizing arm 376 to prevent lateral rocking ofthe shim. Alternatively, cutout regions 378 may be removed and the shimmay be allowed to rotate 360 degrees. The shim 374 has at least onenotch 382 that is sized and dimensioned to snugly mate with the track 46(specifically the dove tail grooves 48 formed on the interior ofretractor blade 38) and may travel up and down the length of theretractor blade 38.

As depicted in the flowchart of FIG. 62, one example method forutilizing the systems, implants, and instruments described above is setforth below. A lateral access surgical corridor is formed in the patient(step 400), the disc space is prepared (step 402), and the anteriorlongitudinal ligament is resected (step 404) as previously explained.Next, at step 406, a guided clip associated with the insertioninstrument (either integral to or removably coupled to) is engaged withthe track on a retractor blade used to create the access corridor. Theimplant is then inserted into the disc space (step 408) as the guideclip translates down the track in the retractor blade. Adjustments canbe made to the implant insitu as needed while minimizing the likelihoodthat the implant 200 will be expelled from its optimal position. At step410 the inserter can be decoupled from the implant 200 and removed fromthe access corridor. Depending on the type of hyper-lordotic implantselection, an additional step of securing the implant with fixationanchors may also be appropriate. Having been deposited in the discspace, the implant facilitates spinal fusion over time by maintainingthe restored curvature as natural bone growth occurs through and/or pastthe implant, resulting in the formation of a boney bridge extendingbetween the adjacent vertebral bodies.

While this invention has been described in terms of a best mode forachieving this invention's objectives, it will be appreciated by thoseskilled in the art that variations may be accomplished in view of theseteachings without deviating from the spirit or scope of the invention.For example, particularly at L5-S1 where the pelvic bone makes a lateralaccess approach difficult, an antero-lateral approach similar to theapproach utilized during appendectomies may be utilized.

What is claimed is:
 1. A method for correcting sagittal imbalance of alumbar spine, comprising the steps of: a) creating an operative corridorthat provides access to a targeted spinal disc via a lateral approach byinserting an access system along a lateral, trans-psoas path to thetargeted spinal disc, the access system comprising a stimulationelectrode that is inserted under conditions wherein an electricalstimulation signal is delivered through said stimulation electrode fornerve monitoring when the stimulation electrode is positioned in thelateral, trans-psoas path; b) inserting a cutting device through thelateral operative corridor and severing the Anterior LongitudinalLigament (ALL); and c) connecting an insertion instrument to a firstretractor blade forming a portion of the border of the operativecorridor, the insertion instrument having an implant for positioningbetween the adjacent vertebral bodies bordering the targeted disc spacecoupled thereto; and d) advancing the insertion instrument along theretractor blade to position the implant between the adjacent vertebralbodies.
 2. The method of claim 1, wherein the cutting device includes ablade.
 3. The method of claim 2, wherein the blade is situated betweentwo finger extensions.
 4. The method of claim 1, wherein the cuttingdevice includes an anode electrode.
 5. The method of claim 4, wherein aninsulated retractor is positioned between the ALL and the great vesselsprior to activating electrical current that cuts the ALL.
 6. The methodof claim 1, wherein the implant has an upper surface to contact a firstvertebra of the adjacent vertebrae when the implant is positioned withinthe interbody space, a lower surface to contact a second vertebra of theadjacent vertebrae when the implant is positioned within the interbodyspace, a distal wall, a proximal wall, an anterior sidewall that facesanteriorly when the implant is positioned within the interbody space,and a posterior sidewall that faces posteriorly when the implant ispositioned within the interbody space, the implant further having amaximum longitudinal length extending from a proximal end of theproximal wall to a distal end of the distal wall, a width extending fromthe anterior end of the anterior sidewall to the posterior end of theposterior sidewall, the maximum longitudinal length being at least 40mm, an anterior height extending from the upper surface to the lowersurface at the anterior sidewall and a posterior height extending fromthe upper surface to the lower surface at the posterior sidewall, theanterior height being greater than the posterior height such that theupper and lower surfaces increase in slope from the posterior sidewallto the anterior sidewall forming an angle at least 20 degrees.
 7. Themethod of claim 6, including the additional step of anchoring theimplant in position between the first vertebra and second vertebra. 8.The method of claim 7, wherein the proximal sidewall includes anextension tab that abuts a lateral aspect of at least one of the firstvertebra and second vertebra when the implant is positioned in theintervertebral space, the extension tab including at least one apertureand the step of anchoring the implant comprises advancing an anchorthrough the at least one aperture into one of the first and secondvertebra.
 9. The method of claim 8, wherein the extension tab includesan upper portion including a first aperture that abuts a lateral aspectof the first vertebra and a lower portion including a second aperturethat abuts a lateral aspect of the second vertebra, and wherein the stepof anchoring the implant comprises advancing an anchor through the firstaperture into the first vertebra and advancing a second anchor throughthe second aperture into the second vertebra.
 10. The method of claim 6,wherein the upper surface and lower surface are planar surfaces.
 11. Themethod of claim 6, wherein the upper surface and lower surfaces areconvex surfaces.
 12. The method of claim 6, wherein the implant is afusion implant and includes at least one fusion aperture opening in theupper surface and lower surface to permit bone growth between the firstvertebra and second vertebra.
 13. The method of claim 12, comprising theadditional step of depositing bone growth promoting substances withinthe at least one fusion aperture before, during, and/or, after advancingthe implant into the intervertebral disc space.
 14. The method of claim6, wherein the top surface includes anti-migration features that contactthe first vertebra and the bottom surface includes anti-migrationfeatures that contact the lower vertebra.
 15. The method of claim 1,wherein the step of severing the ALL comprises protecting the greatvessels while the ALL is being severed.
 16. The method of claim 1,wherein the access system comprises at least one dilator having thestimulation electrode situated on a distal end and a retractor thatslides over the at least one dilator in a first configuration, andthereafter adjusts to a second configuration to form the operativecorridor, wherein the retractor includes the first retractor blade. 17.The method claim 16, wherein the nerve monitoring includes determining aproximity and direction to a nerve located in the psoas muscle.
 18. Themethod of claim 17, wherein the nerve monitoring is used to position theinitial dilator as posterior as possible while remaining anterior to thenerve.
 19. The method of claim 18, wherein the retractor includes aplurality of blades, one of the plurality of blades being a posteriorblade and comprising the additional step of fixing the position of theposterior blade just anterior to the nerve prior to adjusting to thesecond configuration such that adjusting to the second configurationcomprises moving at least one of the plurality of blades away from theposterior blade.
 20. The method of claim 19, wherein the first retractorblade is the posterior retractor blade.
 21. The method of claim 20,wherein connecting the insertion instrument to the first retractor bladeincludes slideably engaging a guide piece of the insertion instrumentinto a track of the first retractor blade.
 22. The method of claim 21,wherein the guide piece rotates in two axes relative to a longitudinalaxis of the insertion instrument such that the anterior-posteriorposition and cephalad-caudal position of the implant is adjustablerelative to the first retractor blade.